Technical Field
The present invention relates generally to bias control for optical modulators, and more particularly, to centralized automatic bias control for multiple optical modulators.
Description of the Related Art
Optical modulators made from, for example, Lithium Niobate (LiNbO3) play an important role in optical communication by performing electrical-optical conversions. Optical modulators are currently capable of transferring electrical binary data to the phase and intensity of optical fields, thereby enabling cost-effective long-haul transmission. However, optical modulators suffer from temperature sensitivity, and biases of optical modulators are susceptible to temperature fluctuation due to, for example, room temperature and driver heating.
It is desirable to have an automatic bias controller (ABC) circuit to control the optical modulator automatically to achieve the best signal quality. Even though ABC systems and methods have been implemented to adjust the bias effectively, those systems and methods can only be applied to a single modulator, as there is currently no systems or methods which work in systems including multiple modulators. The use of multiple modulators is quite prevalent in future 400 G and beyond optical systems where, for example, multiple carriers/modulators are employed to produce multiple sub-channels from one transponder. Conventional systems are only capable of employing a dedicated ABC circuit for controlling a single modulator. However, the advance of 400 G and beyond transmission employs multiple modulators to produce multiple carriers, and there are currently no systems capable of centrally controlling multiple modulators using a same hardware platform to stabilize all modulators in one transponder.